This invention relates to optical instruments, and more particularly to an optical instrument of a binocular type arranged to be supported upon the head of a doctor, in proper position before the eyes of the doctor, and providing an illumination system for lighting objects to be viewed through the instrument.
Prior to this invention, Otolaryngologists had their choice of optical operating aids limited to general purpose types. These included large, floor-stand mounted microscopes with built in light sources; spectacle frame or headband mounted loupe-type magnifiers; fiber optic or incandescent light sources mounted on headbands; and ambient light reflectors. For most of these devices, changing features means changing headbands. The most useful of these devices for nasal surgery, specifically, would be the magnifying loupes coupled with a fiber optic light source mounted to a headband. These would be adequate for procedures done on a relatively flat field, but they do not give a stereoscopic view down deep, narrow cavities, such as nasal passages.
The binocular viewing body of the present invention has simularities to binocular indirect ophthalmoscopes such as found in U.S. Pat. No. 4,015,898 to K. E. Schirmer; U.S. Pat. No. 3,963,329 to J. G. Stumpf; U.S. Pat. No. 3,582,191 to D. N. Cohen, et al; and U.S. Pat. No. 2,757,574 to M. R. Thorburn. All contain a four mirror system which reduces the angle extending from the observed object and the left and right pupils of the observer. All contain eyepieces which can slide laterally to accomodate the interpupillary distance of the observer. The Stumpf ophthalmoscope comes closest to the present invention's viewing body. However, unlike Stumpf, with the present invention it is not necessary to set the eyepieces at a substantially greater distance than the ideal interpupillary distance to achieve an observation angle of less than one degree. This increases field of view and ease of use.
The magnification system of the present invention is designed so that lenses are readily attached to the front of the viewing body and to each eyepiece to form a Galilean telescopic system similar to the Poole attachment for the Keeler binocular indirect ophthalmoscope. The Poole attachment utilizes a variable focus system moving the viewing lens through a focusing range of 30-60 mm. This creates a superimposed zoom magnification range. However, to attain this magnification, the surgeon must move closer to the surgical site. This is a serious problem for an Otolaryngologist because of the resulting interference with his long, hand-held surgical instruments. The improvement in the present invention is that lenses of the present invention have various magnifications, but all are prefocused in the range of sixteen to twenty inches. This means that during a surgical procedure lenses of different magnifications may be interchanged without requiring a change in the working distance from the surgical site. This makes the present invention more suitable for ear, nose and throat surgery as opposed to the Poole/Keeler orientation toward eye surgery.
The present invention uses a fiber optics light source for illumination. There are several headband mounted devices for projecting and controlling the light from a fiber optics cable in the prior art. Included among the prior art are U.S. Pat. Nos. 4,290,422; 4,101,709; and 3,745,993. All such devices use one or more lenses to collect the light and project it as a spot to the surgical site. All use a mirror set at forty-five degrees between the cable and the exit lens to keep the unit compact and coaxial with the observer's line of sight.
The primary purpose of the present invention is to provide the Otolaryngologist a stereoscopic view down deep, narrow cavities while still providing a device useful for magnifying flat fields or for just illuminating a site. Present loupes, microscopes, and fiber optic light sources used for nasal surgery give a lighted view but with only one eye at a time since they do not reduce the interpupillary distance of the observer.
There are several types of indirect ophthalmoscopes that will reduce the interpupillary angle, and some that will also provide a magnified view of the surgical site like this invention. However, devices designed for eye surgery have serious drawbacks when used for nasal surgery. Eye surgery only requires use of the device for several minutes. Nasal surgery requires continuous use of the device for several hours. Ophthalmoscopes, especially those with magnifying attachments, are too large. They interfere with the long, hand-held surgical instruments used by Otolaryngologists. Ophthalmoscopes are also too hot and too heavy to be used continuously during hours-long procedures.